Clinical characteristics and risk factors for a distinct pustular psoriasis flare after withdrawal of biologics in plaque psoriasis.

BACKGROUND: Although biologics are effective in treating psoriasis, a subset of patients experience severe relapse after treatment discontinuation. OBJECTIVE: To delineate the features and risk factors for a distinct pustular psoriasis flare following biologic withdrawal. METHODS: This multicenter study included treatment episodes from psoriasis patients who responded to and subsequently discontinued biologic therapy between 2011 and 2025. Clinical features of this distinct pustular psoriasis flare were characterized and associated factors were assessed using a generalized estimating equation model (GEE). RESULTS: This pustular psoriasis flares occurred in 86 of 1,198 treatment episodes (7.2%) and were characterized by painful, diffuse, intense erythema with pustules and swelling, predominantly involving the lower limbs. The occurrence of these flares increased with a higher number of cycles of biologic withdrawal-relapse. A family history of psoriasis, concomitant psoriatic arthritis, a prior episode of this flare phenotype, a higher number of previous biologic withdrawal-relapse episodes, and longer time to achieve PASI 50 during biologic therapy were independently associated with this distinct pustular psoriasis flare. LIMITATIONS: Non-randomized allocation of treatment and lack of histological and molecular data. CONCLUSIONS: Vigilant monitoring and early treatment resumption are recommended for patients with risk factors for pustular psoriasis flares after biologic withdrawal.